Substrates

It comes down to chemistry So, how can you prepare for or understand the likelihood of scalping or tainting? The first thing to realize is that polymer films are just chemicals and that flavors and aromas also are just chemicals or chemical blends. If we go back to our early chemistry where we learned that “like dissolves like,” we can get a clue perhaps. So salt dissolves in water, but not gasoline; sugar dissolves in both water and gasoline; and salt does not dissolve in gasoline. Recognizing that polymers can be viewed as “solvents,” you can get a clue as to what flavors and aromas are “like” the polymer. You should expect that nonpolar polyolefins, such as polyethylene and polypropylene, will have different solubility (or scalping) potentials than those for more polar polymers such as polyesters, nylons, EVOH, etc.

When I am presented with a question relating scalping, tainting or perhaps film and lamination failures with specific packaged products, I first determine what the chemical constituents of the product are to try and identify the type or class of chemical the product contains. Next, I go to tables of chemical resistance for the polymer of the film or package components and look for chemical analogs of the flavor and aroma components. This can give insights into the likelihood of a chemical interaction and relative solubility of the additives in the polymers. Then, if the specific product components are known, the exact details of the scalping or tainting must be determined experimentally using chemical analysis or trained taste panels.

Working the other direction for tainting, the composition of the product, such as high- or low-fat concentrations can give insights as to the likelihood of film-additive migration into the product. This is, in essence, the basis for many of the FDA extraction tests for product/film interactions where the time, temperature and solvent of the extraction testing is varied to judge which class of products you could expect to obtain FDA compliance for a film or packaging component.

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Dr. Eldridge M. Mount

This Technical Topic Channel covers the manufacture and application of all types of substrates. It is moderated by Dr. Eldridge M. Mount, and includes White Papers, questions from readers and comments on industry issues.